With Lumion we never intended to replace VRay but for all cases when you don't need a 100% ray traced solution it is very beautiful.
You'll lose some realism but the increased speed opens up an entire gamut of new options. Even though we developed Lumion as a movie making tool in v1.0 we already have many customers using Lumion for live presentations. They simply fire up the editor while sitting with a customer to give them impressions of design.
The future for us is to boost realism to get closer to VRay renders but there's also a lot we can do in entirely different directions. Think about things like traffic, interaction and many other things. There is just so much you can do once everything is realtime!